Critical field and Shubnikov-de Haas oscillations of k-(ET)2Cu(NCS)2 under pressure

TL;DR

This study measures how the critical magnetic field and Shubnikov-de Haas oscillations in k-(ET)2Cu(NCS)2 change under pressure, revealing significant suppression of superconductivity and insights into electronic properties.

Contribution

It introduces a novel experimental setup combining a tank circuit and diamond anvil cell to measure pressure-dependent superconducting and normal state properties in organic superconductor k-(ET)2Cu(NCS)2.

Findings

Critical field decreases by over 90% within 2 kbar.

The H_c2(θ) phase diagram aligns with weakly coupled layered superconductor theory.

Shubnikov-de Haas frequency increases at 44 T/kbar.

Abstract

A tuned tank circuit in combination with a nonmetallic diamond anvil cell has been successfully used to measure the change in critical field with angle in k-(ET)2Cu(NCS)2 at pressures up to 1.75 kbar and at temperatures down to 70 mK. The critical field has been found to decrease by more than 90% within less than 2 kbar and at a much higher rate for the field applied parallel to the conducting planes. For this orientation, at 1.75 kbar, we have seen a clear change from the ambient pressure behavior of the critical field with temperature at low temperatures. Up to P = 1.75 kbar, the H_c2($\theta $) phase diagram is in good agreement with the theoretical prediction for weakly coupled layered superconductors. We have also succeeded in measuring oscillations in the resistivity of the normal state at higher magnetic field. The $\alpha$-orbit Shubnikov-de Haas frequency was found to increase at a rate of 44 T/kbar. Our experiment opens the possibility for further investigations of the effective mass with pressure, especially because the setup is suitable for pulse fields as well.